The yield of bond funds can be understood as the yield of bond investment (bond funds actually mainly invest in bonds, and the yield of bond fund investment only considers the current income, regardless of the income of bonds held to maturity). As for the bond yield to maturity (generally linked to the market interest rate), it is not the yield of bond investment, but the yield to maturity of bonds (referring to the annual yield of bonds held until now). Many people who don't understand bond investment will equate bond investment yield with bonds. There are two aspects to the income from bond investment. On the one hand, the interest paid by bonds, on the other hand, the net price of bonds (the so-called net price is the price of bonds without accrued interest) fluctuates. For the first aspect, the interest paid by bonds can be understood as the coupon rate of bonds, which is not difficult to understand. For the second aspect, it is more critical. The fluctuation of bond prices often depends on the market interest rate. If the market interest rate rises, the bond price will fall, mainly because the cash flow of the bond is predictable in the case of unexpected bond default (the coupon rate of the bond is generally fixed, and the principal or agreed resale price of the bond due for repayment is also fixed). On the premise of predictable cash flow, the increase of interest rate will lead to the decrease of the amount of cash flow converted into present value, which will lead to the decrease of bond price and the increase of bond yield to maturity. However, the yield of bond investment will fall instead. The main reason is that the profit of bond investment is in two aspects. On the one hand, it remains unchanged, but on the other hand, it is obviously lost, which will lead to a decline in bond investment yield. On the contrary, when the market interest rate falls, the situation is also the opposite. Therefore, when the market interest rate drops, the income of bond funds will rise, while when the market interest rate rises, the income of bond funds will fall.